/*
 * Copyright 2008 The Apache Software Foundation Licensed under the Apache
 * License, Version 2.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law
 * or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */

package org.apache.ibatis.ibator.internal.util;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;

import org.apache.ibatis.ibator.internal.util.messages.Messages;

/**
 * This class holds methods useful for constructing custom classloaders in
 * ibator.
 * 
 * @author Jeff Butler
 */
public class ClassloaderUtility
{

	/**
	 * Utility Class - No Instances
	 */
	private ClassloaderUtility()
	{
	}

	public static ClassLoader getCustomClassloader(List<String> entries)
	{
		List<URL> urls = new ArrayList<URL>();
		File file;

		if (entries != null)
		{
			for (String classPathEntry : entries)
			{
				file = new File(classPathEntry);
				if (!file.exists())
				{
					throw new RuntimeException(Messages.getString(
							"RuntimeError.9", classPathEntry)); //$NON-NLS-1$
				}

				try
				{
					urls.add(file.toURI().toURL());
				}
				catch (MalformedURLException e)
				{
					// this shouldn't happen, but just in case...
					throw new RuntimeException(Messages.getString(
							"RuntimeError.9", classPathEntry)); //$NON-NLS-1$
				}
			}
		}

		ClassLoader parent = Thread.currentThread().getContextClassLoader();

		URLClassLoader ucl = new URLClassLoader(urls.toArray(new URL[urls
				.size()]), parent);

		return ucl;
	}
}
